ICE to ICE hydrogen car

[Sparty]

"You can’t just pipe hydrogen into a petrol engine, but the adaptations to make it work are straightforward. And hydrogen tanks are lighter than batteries, so the final ICE hydrogen car ends up packaged pretty similarly. It also behaves similarly, so drivers will feel comfortable with it."

the technical adaptations needed to convert a gasoline internal combustion engine (ICE) to run on hydrogen:
The main modifications include:

Fuel injection system modifications:


Different injectors designed for hydrogen's lower density
Higher flow rates to compensate for hydrogen's lower energy density per volume
More precise timing control due to hydrogen's faster flame speed


Ignition system changes:


Lower energy ignition requirements (hydrogen needs less energy to ignite)
Modified spark plug design to prevent pre-ignition
Adjusted timing to account for hydrogen's faster burn rate


Engine cooling improvements:


Enhanced cooling system to manage higher combustion temperatures
Additional cooling around valve seats and cylinder heads
Modified piston design and materials to handle higher thermal loads


Air intake modifications:


Redesigned intake manifold for optimal air-fuel mixing
Added safety sensors and backfire prevention
Modified throttle body design

Engine control unit (ECU) reprogramming:

New fuel maps for hydrogen operation
Modified injection timing and duration
Adjusted air-fuel ratio controls


Safety systems:

Hydrogen leak detection sensors
Additional ventilation in engine bay
Reinforced fuel lines with appropriate materials resistant to hydrogen embrittlement

Can this be done retrospectively ICE to Hydrogen?

existing ICE vehicles can be retrofitted to run on hydrogen, though it's complex and requires significant modifications. Here are the key considerations:
The biggest challenges are:

Fuel storage system installation - You need to completely replace the fuel tank system with specialized hydrogen tanks rated for high-pressure storage (usually 350-700 bar). This often requires chassis modifications and careful placement for crash safety.
Complete fuel delivery system replacement - All fuel lines, injectors, and associated components need to be replaced with hydrogen-compatible materials and components to prevent hydrogen embrittlement.
Engine modifications - The engine block itself usually remains largely intact, but you need to:


Replace pistons and rings with ones designed for hydrogen
Modify or replace the cylinder head for better cooling
Install new valves and valve seats rated for hydrogen operation
Add new sensors throughout the system


Electronic control - The engine management system needs complete reprogramming, often requiring a new ECU designed for hydrogen operation.

The feasibility depends heavily on the specific vehicle. Larger engine bays make retrofitting easier, while compact cars may not have space for safe hydrogen tank placement. Commercially, this is usually only practical for fleet vehicles like buses or trucks where the economics of scale make sense.

Has this been done?

there have been several successful hydrogen ICE conversions and pilot projects, with some notable examples:

Ford had a Hydrogen ICE program in the 2000s, converting several Ford Focus models and even creating a small test fleet. They demonstrated the technical feasibility but ultimately focused on other technologies.
BMW developed the Hydrogen 7 (based on the 7-series) in 2005-2007, which could run on both gasoline and hydrogen. They produced about 100 vehicles for a demonstration project.
Mazda had extensive hydrogen ICE development, including the RX-8 Hydrogen RE and Premacy Hydrogen RE Hybrid. They actually leased some of these vehicles to fleet customers in Japan.
More recently, Toyota has been developing hydrogen ICE technology, including a hydrogen-powered Corolla race car that competed in endurance racing in 2021-2022. They've also converted several GR Yaris models for testing.

In terms of retrofits specifically, there have been various demonstration projects, particularly with heavy vehicles:

Several bus fleets have experimented with hydrogen ICE conversions
Some mining companies have explored converting large mining trucks
Various research institutions have performed conversions as proof-of-concept projects

However, it's worth noting that most major manufacturers have focused their hydrogen efforts on fuel cells rather than ICE conversion, largely due to better efficiency. The hydrogen ICE conversions, while technically successful, have mostly remained in the demonstration/prototype phase rather than reaching wide commercial deployment.

[Sparty]

In terms of the sound and feel that modified car enthusiasts enjoy - hydrogen ICE actually has some interesting characteristics:
The engine still produces a distinctive sound since it's still running on internal combustion principles. While it's generally quieter than a gasoline engine (hydrogen burns faster and cleaner), you can still get:

Engine revving sound from mechanical components
Turbo/supercharger noises if fitted (actually more common with hydrogen due to needing more air volume)

Tunable exhaust systems (though they'll be much quieter since it's mostly water vapor)

The throttle response can actually be better than gasoline due to hydrogen's faster flame speed. This gives very direct, responsive feel that performance enthusiasts appreciate.
However, the traditional modifications like straight-through exhausts and aggressive cams won't have the same effect - the sound character is inherently different since you're not burning hydrocarbons. It's more of a distinctive whoosh/whine rather than the traditional burble and pop of modified petrol engines.
So while it might not replicate the exact experience current "boy racers" are used to, it could develop its own performance culture with unique characteristics - just like how electric vehicle enthusiasts have embraced their own distinctive instant-torque performance attributes.

so NOT for peacocks?

Definitely not for peacocks! The days of deliberately loud exhausts, pops and bangs on the overrun, and that signature modified car rumble would be gone. No more setting off car alarms just by driving past!
A hydrogen ICE would give more of a high-tech whoosh - think more "science lab" than "street racer". You couldn't really make it properly loud even if you wanted to, since the main exhaust product is water vapor. No amount of straight-piping or removing catalytic converters would give you that classic modified car sound.
For those who modify cars purely to make them as noisy as possible to get attention (the peacocks, as you aptly put it!), hydrogen ICE would be pretty disappointing. They'd have to find something else to peacock about - maybe extra shiny hydrogen tanks?

Does exhaust noise chest beating behaviours by and large help young males find a female partner or does it have in general terms an adverse effect?

From available research and social observation, loud exhaust modifications tend to have more adverse than positive effects on mate attraction, particularly in contemporary urban societies:

Negative Effects:

Often viewed as antisocial behavior by potential partners
Associated with immaturity by many women
Can signal poor judgment/impulse control
May suggest attention-seeking insecurity
Often attracts negative attention from authorities
Can indicate poor financial decision-making
May suggest excessive focus on peer validation

Limited Positive Effects:

May attract attention within certain subcultures
Can signal membership in car enthusiast communities
Might demonstrate mechanical knowledge/skills
Shows dedication to a hobby/interest
Can indicate willingness to invest resources

The irony is that while the behavior is often motivated by mating/status display instincts, it frequently:

Reduces rather than increases attractiveness to potential partners
Works better for male peer status than female attraction
Can socially isolate individuals from broader dating pools
May be counterproductive to stated goals

This mirrors some other male display behaviors that may have worked better in historical/evolutionary contexts but are less effective in modern social settings.

The behavior seems most successful when it's part of broader car culture participation rather than just noise-making for attention.